The aim of the study: by historical and prospective cohort studies to investigate the validity of postconcussion syndrome as a useful clinical entity in adults. The objectives of the study: 1. To determine the prevalence and degree of headache, dizziness and cognitive dysfunction as well as headache diagnoses after concussion and in controls with minor non-head injuries 2-3 years after the trauma and to make a comparison of these symptoms in both groups. 2. To evaluate the degree of all other symptoms attributed to the postconcussion syndrome 2-3 years after concussion and to compare it with the degree of the same symptoms experienced by controls. 3. To determine the prevalence and duration of acute posttraumatic headache. 4. To determine the prevalence and degree of symptoms of the postconcussion syndrome after concussion and in controls 3 months and 1 year after the trauma and to make a comparison of these symptoms in both groups. 5. To compare the severity of symptoms 1 year after the trauma between concussion patients and controls in relation to marital status and education. 6. To evaluate the influence of duration of unconsciousness and anterograde amnesia on the severity of headache and cognitive dysfunction. The present study was unable to confirm the concept of the postconcussion syndrome as a useful diagnostic entity. The postconcussion syndrome has therefore little validity.